Persons living with HIV (PLH) with suppressed viral load are much less likely to transmit their infection to sexual partners, giving rise to a conceptualization of ART as both treatment and also prevention. The success of a treatment-as-prevention strategy on a public health scale requires that a high proportion of all PLH are engaged in care. Although advances are being made in how to link newly-diagnosed PLH to care, nearly half of the one million Americans already diagnosed with HIV infection are living in the community but not presently in treatment. Until these 500,000 PLH are in medical care, their health is threatened and treatment-as-prevention cannot achieve its maximum public health impact. The field presently lacks intervention strategies that can reach out-of-care PLH in the community, an unaddressed gap in the treatment cascade. Because PLH are often socially connected with other HIV+ persons, social network approaches represent a promising way to reach PLH in the community and also deliver intervention. This research will develop and pilot test a novel network-level community intervention to improve care engagement. The mixed-methods research will occur in two phases. The initial qualitative phase will include in-depth interviews with approximately 50 PLH who never entered care, PLH who dropped out of HIV medical care, and other key informants. Data will be analyzed to examine PLH views, motivations, barriers, and facilitators of medical engagement; identify settings and ways to access out-of-care PLH; elicit research input from the PLH community and its stakeholders; and tailor intervention content. The second research phase is a small randomized test-of-concept pilot study to determine preliminary efficacy of the network-level intervention. 10 out-of-care MSM PLH seeds (half African American MSM) will be recruited in the community. Each seed will bring into the study friends known to also by HIV+. When enrolled, these first-ring friends will, in turn, also recruit their own HIV+ friends, resulting in the accrual of 10 2-ring PLH sociocentric networks (expected n=120 individuals). Participants will be assessed at baseline for recent care attendance, CD4+ and HIV viral load, ART adherence, risk practices, and psychosocial characteristics. Five networks will then be randomized to receive the network intervention. Leaders in intervention condition networks will be identified, trained, and guided to deliver ongoing, theory-based, personally tailored advice to PLH friends about treatment benefits and about strategies to enter, remain, and adhere to medical care. We will determine if the intervention increases network member care engagement at 6-month follow up, the primary outcome. Effects of intervention on secondary outcomes of treatment adherence, viral load, and psychosocial scales will be examined. If the exploratory study produces preliminary evidence of benefit, a full-scale trial will later be proposed. The network intervention to be tested has the potential to reach and engage more PLH in the community to enter care, a critical but neglected point in the treatment cascade.